In
response to readers' requests, we have established a helmet FAQ to address some
of the difficult questions asked by cyclists who are often confused by
conflicting information they get about helmet use and its effectiveness. Our
answers are frank and accurate. Unlike many answers on FAQ sites, ours are
based on reliable international research and other sources. Where possible
we've provided links to source material. [Note, we do not attempt to answer
consumer-type questions such as comparison of different brands or how to fit a
helmet. These questions seem to be adequately addressed by other sites. Also
for the purpose of this FAQ, in our terminology, "cycling" excludes
extreme forms of bicycle use like downhill mountain bike racing, where
increased risk is the cost of greater performance.]

We
oppose bicycle helmet laws of any kind because of the damage done in
jurisdictions which have them. We do not advocate the use of helmets, but
neither do we counsel against their use. It is clear from the evidence we
present that cycling is not so dangerous an activity that their use is
particularly justified. We wear no special protective headgear for other every
day activities such as walking and driving a car, even though our heads are
exposed to similar risks for far greater lengths of time.

We
have reason to believe the helmet debate has little to do with safety, and much
more to do with commercial interest and a specific lifestyle advocacy similar
to that which would control what we eat, drink and take into our lungs. If the
debate was about reducing the already low frequency of cyclist head injuries,
then the principal issue would be about whether manufacturing standards should
be modified in order to ensure production of helmets which actually provided a
reasonable amount of protection. Really effective helmets would be of such a
design (i.e. ugly) and construction that few would buy them. Also, there are
downsides to helmet use and scientific reasons to believe they exacerbate
injuries in certain types of impacts. At the moment, a discussion on helmet
problems is not in the interests of helmet manufacturers.

If
the dicussion were about bicycle safety then we would be discussing how we can
get the cycling public to adopt the most effective and proven method of
preventing injuries i.e. responsible behaviour and application of skills when
cycling. Cyclist education addresses over 90% of all cycling accidents. To put
this in perspective, severe head injuries represent less than 2% of all cycling
injuries.

Unfortunately,
North America's focus on helmets has become so obsessive that the already false notion that cycling is dangerous has been
strongly reinforced. It's not surprising that legislators find ready public
acceptance of arbitrary laws which restrict bicycle use on our public roads and
highways. The result is less cycling than otherwise there would be, and fewer
choices for exercise and responsible modes of travel. In this environment,
everyone loses.

This FAQ attempts to cut through current
bicycle helmet hyperbole to provide the facts upon which responsible people can
make measured decisions for themselves.

If
only they were. Helmets which could provide significant protection (if they existed)
would be of such construction that few would care to wear them. Modern bicycle
helmets are designed to mitigate the effect of an impact to the head of a
person falling off a bicycle. At best, they reduce the chance of minor
injuries.

"...
it is impossible to build a helmet that will offer significant impact
protection"

Dr.
George Shively, The Snell Memorial Foundation

"...
helmets will mitigate the effects of falling off your bicycle and striking your
head... If a cyclist is accelerated by a car, then the helmet will not work and
will not prevent a severe or even fatal injury"

2.
Does helmet use save lives or reduce the number of serious head injuries?

Claims of reduction are
very suspect. Such claims surfaced in Australia after introduction of helmet
laws in the early 1990's. It was subsequently discovered that large
reductions in cycling had been ignored.

The rapid increase in helmet use in
Australia following legislation showed no helmet benefit. {9} The rates of decline in
cycling equaled or exceeded rates of decline of cyclist head injuries. {10}
Likewise, New Zealand experienced a dramatic rise in voluntary use prior to
mandating but no reduction in the rate of serious head
injuries. Reductions in cycling also were experienced. {10}

We've heard these
anecdotes, but the stories you won't hear are the more frequent ones of
bareheaded cyclists falling off their bikes without incurring head injuries.
They don't lend themselves well to story-telling.

The "helmet-saved-my-life" stories
are mostly hyperbole. A plausible explanation for them is that a helmet is a
fragile piece of styrofoam which is larger than the head it is on. A helmet on
the head of a cyclist who falls from a bicycle on to a hard surface is almost
certain to come into contact with the surface and be damaged. A cracked helmet
is not proof of protection but rather of a failed helmet{8a}. It's all too easy
then to assume a serious head injury would have been incurred without the
helmet. Physicians are often the source of these stories, but they have no
particular competence in the mechanics of a bicycle accident. When a helmet
gets trashed it may well have prevented a nasty bump or even saved a few
stitches, but the odds it saved a life are about the same as winning the
jackpot in a lottery.

Helmets are tested in the
lab for straight line (linear) blows only. Test procedures set by standards bodies like Snell,
ANSI, and CPSC
require a helmet containing a 5kg (11lbs) rigid headform to be dropped onto a
flat anvil from a height of 1.5 to 2.0 metres (5ft to 6ft 8in). If more than
300g's is imparted to the headform the helmet cannot be certified.

The outer shell of the 1980's hard shell
helmet is designed to spread the force of an impact over a greater area of the
head. The micro-shell of modern helmets does not do this, deforming instead and
allowing the liner to start compressing at the point of impact. Whether this is
good or not is open to question.

All shelled helmets reduce friction in a
slide compared to no-shell helmets. The helmet's liner is made of foam
sufficiently stiff that the head inevitably will absorb some of the impact. The
stiffer the liner, the more shock the head will absorb. Theoretically, the
liner is supposed to limit the deceleration for a typical fall on to a flat
hard surface to a sub-lethal level, ie. less 300g's, by absorbing energy.
Sub-lethal means anything from a very bad concussion to a coma. If a blow is of
such severity that the liner is crushed to its minimum thickness, excess energy
is absorbed by the head and the blow is likely to be lethal.

The medical profession now believes that
even lesser accelerations can produce serious injury and that the 300g level is
too high. However, it is unlikely that helmet standards will be raised to
provide significant protection because the industry doesn't believe that
consumers would buy the resulting products. The trend is in the opposite
direction. In Australia, the standard was actually lowered because helmets
produced under the old standard did not meet with market acceptance.
Manufacturers are presently responding to market demand for helmets which
improve air-flow inside the helmet and to fashion by manufacturing helmets with
more holes them. While these pass standard tests, they spread impacts over a
smaller area of the head, so when an impact occurs it will be more concentrated
around the center of the impact.

Yes and no.
While the biomechanics of what happens to a cyclist in an accident is very complex,
industry tests are extremely rudimentary. The primary
objective of head protection is the minimisation of brain tissue distortion on impact. {7a}
Tests attempt to replicate a fall from a bicycle where a helmeted head directly hits a fixed solid object.
Because the use of a rigid headform is prescribed and the headform's only
resemblance to a human head is its shape, test procedures are unable to
simulate the effect on a head's bone and soft tissue. In the test, the foam
liner being less dense than the headform starts to crush on impact. The test therefore favours stiffer padding.
In a real crash, a head and its brain will distort and absorb energy causing cranium distress.
An attempt to refute this assertion has been made {8} using a modified head form
simulating scalp and hair, but the test has the same limitation of an industry test in that it did did not address
the issue of measuring the resulting forces in the brain and the deformation of brain tissue.
A report prepared by the Australian Transport Safety Bureau states that research on foam
liners from fatal accidents showed little or no evidence of impact damage and
that some research reported that the human skull distorted rather than the hard
stiff foam liner, resulting in brain damage or death.{8a}

Industry tests exclude any possibility of
measuring what might happen inside the skull where brain tissue contorts,
rotates and tears as the skull is impacted. The result is helmets being
manufactured which optimize padding stiffness even though softer padding could
provide better overall protection. The rigid headform is capable of crushing
hard-stiff foam liners in helmets, and manufacturers have had to provide
high-density liners to pass the impact attenuation and penetration tests. In
collisions, the human head is incapable of bending or compressing the foam and
the unyielding characteristics of the headform is quite inappropriate as a
simulation of the human head{8a}. Reflecting concern over this and the
effectiveness of existing helmets, the Canadian Standards Association has
altered its test specifications for children's helmets to ensure they are
constructed of softer padding.

No. Sharp, high speed objects
are likely to penetrate helmets particularly those with many vent openings.
Also, helmet tests monitor the effect of linear force but not rotational force.
A blow which is not square on centre, i.e. not linear, will rotate the head.
Diffuse injuries - the most serious and common type of brain injuries - result
from rotational stresses on the brain. Linear force on the other hand, result
in focal or localized injuries rather than diffuse injuries.

It has not been ruled out that the added
mass, size and surface texture of a helmet may make the rotational effect more
severe. A "safety" device which has been shown undeniably to assist
in rotation and increase the risk of diffuse brain injury is the headrest on
car seats in rear-end crashes. Nothing has been shown one way or another
though, for bicycle helmets. When acquiring new helmets, buyers should consider
helmets which are spherical in shape as they are more likely to minimize
rotational effect than the trendy duck-shape aerodynamic helmets.

8.
None of us wear helmets while walking or riding in cars*. Is there any good
reason to wear them on bicycles?

Yes, if it makes people
feel better, they should wear them. But they should not think of them as a
panacea or a substitute for the application of responsible riding habits. Many
folks have unreasonable expectations that their heads will be protected by
helmets in a high speed crashes with cars.

Many of the same people wear their helmets
because they perceive there is a high risk of incurring a head injury while
cycling. Skills among cyclists vary, so on an individual basis, some cyclists
are at greater risk than others, but unless such individuals are deliberately
reckless, their risk of incurring head injuries is
extremely low.

Compare cycling with similar activities.
Most people don't overly worry about car use and walking* even though they may
expose individuals to greater risks. For example, half of America's 40,000
motor vehicle deaths are from head injury. According to the US Center for
Disease Control and Prevention,over 30% of all 50,000 US
traumatic brain injury fatalities annually result from car use. Yet, less than
1% result from bicycle use. The pedestrian figure is about 7%. Australian
figures {10} show that fatality rates attributable to head injury (based on
time exposed) are approximately the same for cyclists and users of motor
vehicles. The pedestrian rate is almost twice that of cyclists. Despite these
facts, the average person fears bicycle use far more than walking or riding in
a car. This difference in perception derives from over zealous promotion of
bicycle helmets where, in order to get cyclists to wear them, it's necessary to
exploit the fears of cyclists by making cycling appear dangerous. The end
result is that the general public gets the wrong message about bicycling and
believe that helmets are a necessity.

* [Although the
obsession over use of helmets has now spread to walking (
in Japan) and
riding in cars (in Australia)]

No, not for cyclists who
operate their bicycles sensibly and abide by the basic vehicular rules of the
road. That's not to say there are no risks. Some extreme forms of bicycle use
such as downhill mountain bike racing appear to involve increased risk-taking.
It is appropriate to wear specialized equipment for these, but they should not
be confused with utility and leisure uses of bicycles. Any activity involves
risk. Climbing the stairs and walking could be considered risky activities
based on fatal accident statistics. Each of these activities account for more
premature deaths than cycling. Cyclists in North America, even with their low
average skill level and often irresponsible behaviour, suffer a lower fatality rate (measured in time exposed), than
those participating in other common activities such as car use, swimming and
water skiing. {11} Hospitals report no particular epidemic of head injuries
among cyclists. Life insurance companies don't increase premiums for bareheaded
cyclists. They are more likely to offer a discount to cyclists because of the
health benefits derived from cycling.

Car use may be the most dangerous of all
activities in terms of accidental deaths, and two articles - one from New Zealand and one from Australia
- suggest that the widespread use of helmets (as in car racing) could reduce
the number of these deaths. However, it's highly improbable that motorists will
perceive their risk great enough to induce them to wear helmets. (Car helmets
have recently become available in Australia.)

No doubt for some it does,
although such changes may not result from any conscious action by cyclists.
Studies of the effect on behaviour
of other safety equipment {1},{13} show strong correlations between use of
safety equipment and increased risk taking. This is the "risk
compensation" effect. It has been associated with the use of anti-lock
braking systems, car seat belts, automobile air bags, ice hockey helmets, and
football helmets. Many mountain bikers admit that they would never subject
themselves to the hazards of some trails if they weren't wearing helmets. Other
cyclists have said they enjoy cycling bareheaded but won't expose themselves to
[what they perceive as] higher levels of risk on busy arterial roads unless
they are wearing helmets.

Both the latter examples imply that some
cyclists change their behaviour with helmet use.

11.
What if my children refuse to ride their bicycles when forced to wear a helmet?
Is "no helmet, no cycling" a good rule?

Not from a health point
of view.

Scrapes, bruises and other minor injuries
from physical activities like cycling are a normal part of growing up. Parents
of the current generation grew up cycling without helmets. There was no problem
then, so why is there a problem now? Children are already less healthy than the
children of the previous generation. Child obesity has risen rapidly in the
last twenty years partly because of poor diet but also because kids exercise
less.

"The gain of 'life years' through
improved fitness among regular cyclists, and thus their increased longevity
exceeds the loss of 'life years' in cycle fatalities (British Medical Association,
1992). An analysis based on the life expectancy of each cyclist killed in road
accidents using actuarial data, and the increased longevity of those engaging
in exercise regimes several times a week compared with those leading relatively
sedentary lives, has shown that, even in the current cycle hostile environment,
the benefits in terms of life years gained, outweigh life years lost in cycling
fatalities by a factor of around 20 to 1."
{3},{7b}

Is it wise to place the benefits of cycling
at risk because of misguided attempts to protect children from every possible
mishap? As long as your children receive proper safe riding instructions they are probably at less
risk of serious injury than they are when taking a ride in the family car (accessed 2008). It's important that
parents don't unintentionally discourage their kids from participating in a
safe, convenient, and healthy activity.

Constant promotion of helmets
diverts attention from effective accident reduction measures and makes cycling
look so dangerous that it scares some people off cycling completely. {8} Head
injuries result from a tiny portion of cycling accidents. A search of the
Internet will show that far too frequently "bike safety" messages
focus exclusively on helmet use. Nine times out of ten, the genuinely effective
measures of acquisition of skills and rider behaviour get little or no
attention at all, yet the skill level of average North American cyclists needs
to be radically raised. Bicycle
transportation engineer, John Forester {7} shows data which indicate
competent cyclists reduce their chances of being involved in an accident by 80%
when compared to unskilled cyclists. 1995 surveys in the cities of Ottawa and
Toronto, Ontario found that the least competent cyclists - sidewalk cyclists -
were more likely than on-road cyclists to wear helmets but less likely to
execute left turns from the left turn lane. It appears they have been convinced
to wear helmets but not to operate bicycles safely {2}.

13.
How should we interpret clinical studies which claim 85% reduction in the risk
of a head injury?

With great skepticism.
The widely publicized 1987 study of cyclists with mostly minor head injuries
received at emergency rooms in five Seattle area hospitals {11} has been
roundly criticized for its flawed methodology {9}. For example, the helmet use
rate of the population control group of kids under 15 gathered from members of
a Group Health Co-operative, was 21.1%, but observed rates of helmet use among
kids on the streets was 3.2% {4} as Frederick Rivara, one of the authors of the
85% claim, knew full well as he particpated in the street survey. This suggests
the control group was not representative of typical cyclists. The case group of
head injured children had a helmet usage rate of 2.1% (3 of 143). This, as a
statistician would know, was well within sampling error of the observed helmet
wearing rate of the kids seen on the street and therefore suggests no benefit
from helmet use. Helmet use among injured kids was actually higher than that on
the street (4% vs. 3%) indicating helmeted kids were showing up more frequently
at hospitals than the general cycling population. If we used these comparisons
and the methods used by the authors, we could say that among children, helmet
use increases the risk of an injury by 33%!

The authors themselves admitted in the
report,

"We cannot completely rule out the
possibility that more cautious cyclists may have chosen to wear helmets and
also had less severe accidents."

Indeed, the first of those conditions is more
than a possibility. There is evidence which shows it to be the case. In an Arizona study {5}, Farris, Spaite et al
found that voluntary helmet users were 2.6 times more likely to stop at stop
signs and 7.1 times more likely to use legal hand signals {8}. It's logical to
assume then that more cautious cyclists will have less severe injuries. The
report concludes that the very strong association of helmet use with safer
riding habits has implications for injury-control efforts aimed at preventing
bicycle-related injuries. In contrast, the authors of the Seattle study, who
are prominent in campaigns to mandate bicycle helmets, have been notoriously
indifferent to injury reduction programs which are based on raising the level
of cyclists' skills.

There are other biases in the Seattle sample
also. We note from the report's data that helmeted patients were from higher
income groups. These may well have been more likely than low income earners to
show up at the hospital emergency rooms when suffering trivial or no injuries
at all. See other
criticisms of the report.

Shedding further doubt on the credibility of
such studies is that, not only has the 85% risk reduction figure not been
replicated among populations which have experienced rapid increases in helmet
use, but studies of these populations have detected NO REDUCTION in the rate of
head injury that can be attributed to helmet use. {9},{11}

A 1997 analysis of US National Highway Transportation
Safety Administration data (to 1995) uncovered no statistically significant
drop in cyclist fatalities in the eight states which have implemented MHL for
at least one year. In the affected age group, New Jersey's fatalities dropped
from four to one in the year following the law, then rose back to five the next
year! California's changed from an average of 34.75 fatalities in the four
years before the law to 34.5 in the two years since the law. Significant drops
in children cycling to school have been reported after the introduction of the
helmet laws. When cyclists quit cycling and turn to sedentary lifestyles, the
general health of populations decline. Everyone among those populations pays
the resulting costs of increased health care.

In the Canadian province of Ontario, a child helmet law is widely ignored by children, parents
and police alike. In the Borough of East York, Ontario, helmet use went up
immediately following the law’s introduction but returned to the pre-law level
within four years {14}{15}. Police forces are already stretched to the limit
dealing with real crime and couldn't enforce the law even if they wanted to.
This has a negative impact on attitudes toward the justice system It sends the
wrong message to young Canadians who already ignore much more important
requirements such as the nighttime lighting law.

It is difficult to see anything but harm arising out of helmet laws. Physician, Dr. Thomas
Demarco sees helmet laws as very damaging. He expressed his views in an article originally published in the Journal of
the Canadian Medical Association.

There's no particular
epidemic of injuries from cycling, but unnecessary injuries are being incurred
because of poor cyclist judgement. Without a doubt, the most effective way of
avoiding injuries are those measures which focus on accident prevention. The
primary accident prevention measure is skills training, particularly for
children. It is 80% effective in reducing risk. You can't get better advice
than that offered by John Forester in his book, Effective Cycling {7}:

"riding so you are
less likely to get into accident situations is the first safety measure;
watchfulness and skill in escaping them is the second."

If cyclists make an effort to acquire the basic
skills and abide by these two principles, their risk of being involved in
serious accidents is miniscule.

Cyclist education programs are available in
most countries. The US national program - Effective Cycling - and its Canadian
equivalent - CAN-BIKE are both based on the teachings of John Forester. Such
programs are usually sponsored by national cycling organizations and delivered
at the local level by bike clubs and other cycling organizations.

{14}Macpherson
A, Macarthur C, To T, Chipman M, Wright J, Parkin P. Economic disparity in
bicycle helmet use by children six years after the introduction of legislation.
Injury Prevention 2006;12:231-35.

§Australian Chris Gillham has analyzed public
records to determine theimpact
on health of Western Australia's compulsory bicycle helmet law.

§British expert witness in bicycle crash litigation,
John Franklin
has material on his web site.

§An international coalition of doctors, scientists,
engineers and other experts make up the Bicycle Helmet Research Foundation . Its web site contains
a comprehensive collection of helmet research and opinion.